Automatic starter control



Sept. 22, 1936. I P MAURER 2,054,987

AUTOMATIC STARTER CONTROL Filed May 12} 1934v T INVENTOR Patented Sept.22, 1936 AUTOMATIC STARTER CONTROL Paul H. Maui-er, Elmira, N. Y.,.assignor to Echpse Machine Company, Elmira, N. Y., a corporation of NewYork Application May 12, 1934, Serial No. 725,371

2 Claims.

The present invention relates to an automatic starter control forinternal combustion engines and more particularly to a device of thesocalled ignition key starter type in which cranking is initiated byclosure of the ignition switch,

and thereafter the starting mechanism is controlled automatically tokeep the engine running as long as the ignition switch remains closed.

In devices of this type in which electromagnetic means energized from anenginedriven generator are used to prevent operation of the startingmechanism, some difficulty has been encountered in certain installationsin designing said electromagnetic means, or so-called lock-out coil, soas to be sufficiently sensitive to prevent actuation of the startingmechanism at the slowest idling speed of the engine, Without overheatingunder normal charging conditions and without appreciably affecting thecharging performance of the generator.

For example, in a typical six volt starter control in which thegenerator lock-out coil has a resistance of about fifteen ohms, there isno over 5 heating and the look-out function is effective down to about0.15 volt corresponding to about 220 R. P. M. of a commercial type ofgenerator, which is satisfactory for many installations. In someinstallations, however, in which the drive 30 ratio from the engine tothe generator approaches unity, it is desirable for the lock-out coil tobe effective at considerably slower generator speeds, and it has beenfound that a lockout coil of about two ohms resistance may be 35 madeeffective down to about 0.06 volt corresponding to a generator speed ofabout 95 R. P. M. This is quite satisfactory as respects the lockoutfunction, but the continued application of full generator voltageoverheats such a coil,

40 and the minimum charging speed of the generator is raised fifty toseventy-five R. P. M. which is undesirable.

It is an object of the present invention to provide a novel automaticstarter control embody- 45 ing improved lock-out means for preventingactuation of the starting mechanism while the engine is self-operative.

It is another object toprovide such a device of the type utilizingcurrent from an engine- 50 driven generator for maintaining the startingmechanism inoperative, embodying provisions for increasing thesensitivity and reliability of the generator control.

. It is a further object to provide such a device 65 which is adaptedfor use with ordinary comly the operation of any of the units of thecom- 10 bination in which it is incorporated.

Further objects and advantages will be apparent from the followingdescription taken in connection with the accompanying drawing in whichthe single figure illustrates in a semi- 15' diagrammatic form apreferred embodiment of the invention.

Referring to the drawing, there is illustrated an electrical system foran internal combustion engine, not shown, comprising a starting circuit20 including a battery I grounded at 2 and connected by a lead 3 to amagnetic starting switch 4 which in turn is connected by a lead 5 to astarting motor SM grounded at 6 to complete the starting circuit. Anengine-driven generator G is also illustrated, which is arranged duringself-operation of the engine to charge the battery 1 by means of a leadi connected through ammeter A to the battery lead 3, the chargingoperation being controlled by a cut-out or reverse current relay 8 ofthe usual type.

A control circuit for the magnetic starting switch is provided includingbattery lead 3, manual switch s, which is preferably the ignition switchof the engine, lead ll, solenoid I2, lead it, fixed contact I4 andmovable contact l5 which is mounted on a spring strip l6 grounded at l!to complete the control circuit.

Electromagnetic means are provided for holding open the control contactsl4, I5 during selfoperation of the engine responsive to voltage producedby the generator G. As here illustrated, this means comprises a solenoidor lock-out coil l8 mounted on a fixed pole piece l9 and arranged toattract a reciprocable plunger 2! which is normally maintained in upperposition as illustrated by means of a spring 22. Plunger 2!, when pulleddownward into engagement with the pole piece I9, actuates a bell cranklever 23, causing a roller 24 on the outer end thereof to engage aWeight member 25 on the end of the spring strip i6 and bend the samebackward to maintain contact l5 out of engagement with contact l4.Solenoid I8 is connected in circuit with generator G by means of a lead26 connecting one end of the for completing the look-out circuit.Closure of the starting circuit is thus prevented by the energization ofsolenoid M3 to a predetermined degree corresponding to the idling speedof the engine.

According to the present invention, the solenoid I8 is designed toperform its lock-out function effectively and reliably by means ofcurrent supplied by the generator when rotating at the slowest idlingspeed of the engine, and means controlled by said solenoid are providedfor protecting the solenoid from the excess voltage produced by thegenerator under charging condi tions which would otherwise causeoverheating and adversely afiect the generator performance. For thispurpose a resistor 28 having a value such as to suitably limit thecurrent passing through the solenoid I8, is connected between the lead21 and the ground, and means in the form of normally closed contacts 29and 3| are provided for short-circuiting said resistance when thevoltage of the generator G is below a predetermined value, said contactsbeing arranged to be opened when the solenoid I8 is energized bygenerator voltage above said predetermined value.

As here illustrated, contact 3| is mounted on a rigid conducting bracket32 which is grounded at 33, while contact 29 is mounted on a conductingspring strip 3 connected to the solenoid ground lead 21. A magneticarmature 35 is mounted on a spring strip 36 and is provided at, its freeend with a block of insulation 31 adapted to engage the free end of thecontact strip 34 and move contact 29 out of engagement with contact 3|.Armature 35 is arranged'to surround the magnetic plunger 2| withcomparatively small clearance and forms a magnetic bridge substantiallycompleting the magnetic circuit of the solenoid l8, which, circuitcomprises pole piece I 9, the container or box 38, a partition 39 insaid box and the plunger 2|. It will be noted that a substantial openingis provided at ill for the plunger 2| where it traverses the partition39, and the armature 35 is arranged to bridge said opening. This causesa large proportion of the flux traversing the magnetic circuit of thesolenoid l8 to flow through the armature 35 When the solenoid isenergized to a predetermined degree higher than that correspondingtoengine idling, the armature is therefore pulled down against thepartition 39, thus opening contacts 29, 3|.

' Substantial lost motion indicated at 42 is provided between the blockof insulation 31 and the end of the spring strip 34 in order that thecontacts 29, 3| shall not be opened until the armature 35 has beenpulled down quite close to the partition 39. This arrangement insuresagainst the possibility of a fluttering action of contacts voltage.

29, 3| due to the introduction of the resistor 28 in the circuit ofsolenoid l8 by the opening of said contacts and the consequent weakeningof the solenoid. 1

It will be understood that the spring strip 36 forming the mounting forthe armature 35 has sufiicient stiffness to insure release of thearmature 35 and closure of contacts 29, 3| at a substantially highervoltage of the generator G than the voltage at which plunger 2| will bereleased to permit closure of the control contacts I l, l5. The voltageat which the armature 35 is pulled down to open contacts 29, 3| is,however, preferably substantially below the charging voltage of thegenerator in order that the solenoid l8 may be adequately protected fromsuch charging The combined resistance of the solenoid l8 and theresistor 28 is preferably equal to or greater than the resistance of theordinary generator lock-out coils used in automatic starter controls ofthis character, so that the rotational speed of the generator at whichcharging commences is not increased by the use of the present device ascompared to the ordinary less sensitive types of starter controls.

In one satisfactory embodiment of this invention, for example, thelook-out coil l8 has a resistance of about two ohms, the resistor 28 hasa value of about thirteen ohms, the short-circuiting contacts 29, 3|open at about 4.5 volts, and close at about 3 volts, and the relayplunger is released at about 0.06 volt; Since the resistance of thelock-out circuit external to the generator is raised to fifteen ohms bythe insertion of the resistor before the generator gets up to chargingspeed, the minimum charging speed of the generator is not appreciablyincreased by this device.

In the operation of this device'and starting with the parts in thepositions illustrated, closure of the ignition switch 9 completes thecontrol cir-' cuit through battery I, lead 3, ammeter A, lead 1|, switchsolenoid l2, lead l3, contacts. |4, |5,

spring strip l6 and ground connection H. The consequent energization ofthe switch solenoid l2 causes closure of the starting switch 4, thuscompleting the starting circuit and causing the engine to be cranked.

When the engine becomes operative, the plunger 2| is attractedagainst'the pole piece l9, opening control contacts I4, I 5, and isretained in'that position'by the energization of the solenoid |8 by theengine-driven'generator G. When the engine is running at or near suchspeed as to causethe generator to charge the battery, the solenoid I8 isenergized sufficiently to hold the armature 35 against the partition 39,whereby contacts 29, 3| are held open and the resistor 28 is put inseries with the solenoid l8, thus protecting the same against the fullvoltage of the generator. When the engine slows down nearly to idlingspeed,the weakening of the solenoid l8 by the reduction in the generatorvoltage permits the armature 35 to pull away from the partition 39 andallow contacts 29, 3| to close, thus short-circuiting the resistor 28and permitting all the voltage then produced by the generator to beapplied to the solenoid l8, thus insuring against release of the plunger2| during slow idling of the engine. Should the engine stall for anyreason, however, the complete failure of generator voltage causesdeenergization of the solenoid 8 whereby the plunger 2| is released,permitting the control contacts l4, IE to close and cause the startingoperation to be repeated.

Although but one embodiment of the invention has been shown anddescribed in detail, it will be understood that other embodiments arepossible and various changes may be made in the details and arrangementsof the parts without departing from the spirit of the invention definedin the claims appended hereto. 7

What is claimed is: V

1. In an electrical system for internal combustion engines a startingsystem including a magnetic starting switch, an engine-driven generator,

,a control circuit for said starting switch including normally closedcontacts, electromagnetic means including a plunger responsive to apredetermined voltage of the generator for holding open said contacts,an armature'surrounding said plunger and arranged to be attracted bysaid electromagnetic means, a resistor, and contacts for causing saidstarting switch to open, and means energized by said generator forpreventing closure of the starting switch, a resistor in series withsaid generator-energized means, means including an armature and contactscontrolled thereby actuated during cranking by the batteryenergizedmeans and during self-operation of the engine by the generator-energizedmeans for short-circuiting said resistor upon energization of saidelectromagnetic means below a predeter- 10 mined minimum.

PAUL H. MAURER.

